To mark the occasion, the embassy has released a video highlighting significant moments for the embassy and the Chancery building over the past 50 years.

In the programme from the official opening day, May 23 1964, the embassy was noted as: "being circular as the placement of the 13 stars in the first American flag, it symbolises unity and strength... This form also enables the building to face in all directions, friendly and attractive from any angle".

American architect John M Johansen, in consultation with prominent Irish architect Michael Scott, was faced with a challenging task in designing the building.

It had to fit with the triangular site at Elgin and Pembroke Roads in Ballsbridge, reflect Irish stylistic features and be functional as an embassy as well as being attractive to the eye.

19th and 20th Century adaptations of features found in 5th Century Celtic monuments suggested a circular building utilising pre-cast modular units in its construction.

A "moat" of flowering shrubbery, bridged at the entrance, and a park-like plaza of benches and trees, complete the setting.

The embassy said the building is a concrete expression of the close relationship between Ireland and the United States.

The US first opened a consulate in Ireland in 1859 in a building off Adelaide Road.

It was one of the first countries to recognise the Irish Free State, and in 1927 appointed Frederick A Sterling as an envoy and established a legation in what is now known as the US Ambassador’s Residence in the Phoenix Park.

In 1948 the offices of the legation moved to 15 Merrion Square, Dublin.

The new site in Ballsbridge was announced in 1957 and the construction of the building was begun in 1962 by G & T Crampton Ltd, of Dublin. It was completed in May 1964.

The embassy serves as the headquarters for officials and employees of the US government in Ireland.